Stefanie Joho, 27, in Penn Valley, Pa., Last spring, was treated with Merck's Keytruda for advanced colon cancer. A new study shows that the immunotherapy drug, when combined with chemotherapy, also prolongs survival in patients with advanced lung cancer. (Photo by Michelle Gustafson for The Washington Post)

Patients with newly diagnosed advanced lung cancer who received an immunotherapy drug plus standard chemotherapy lived significantly longer than those who received chemotherapy alone, according to a new study that is expected to change the way such patients are treated.

The report was one of several highly anticipated studies on immunotherapy and lung cancer presented Monday at the annual meeting of the American Association for Cancer Research in Chicago. The studies were published simultaneously by the New England Journal of Medicine on a day that some experts called the "Super Bowl of immunotherapy against lung cancer."

"Immunotherapy combines rapidly with other treatments and by itself, dramatically changing the standard of care for lung cancer," said Leena Gandhi, an oncologist. at NYU Langone Health, who led the study on the combination of immunotherapy and chemotherapy, called Keynote-189. "Instead of chemotherapy is the backbone on which to improve, immunotherapy is now the backbone on which we build."

Lung cancer is the second most common malignancy in the United States, after breast cancer. The American Cancer Society estimates that 234,000 people will be diagnosed with the disease this year, and 154,050 will die from it.

Most patients diagnosed with advanced lung cancer – a disease that has spread beyond its original site – initially receive chemotherapy, which provides only marginal benefit. But the disease is so lethal that many patients do not survive long enough to try second or third line treatments, so researchers are trying to develop and use more effective approaches before.

The test that monopolized much of the interest on Monday is a randomized effectiveness study that involved more than 600 patients not treated with advanced non-squamous non-small cell lung cancer, a common type of the disease. The patients did not have mutations that cause cancer. One group was treated only with chemotherapy, while the other received an immunotherapy medication called Keytruda plus chemotherapy. Some of the results had been previously published, but not specific details.

After a median follow-up time of 10.5 months, Gandhi said that patients in the combination group had a 51 percent lower chance of dying, compared with patients in the chemo-alone arm.

"For the first time, adding another drug has had a significant impact on the long-term prognosis for those patients," he said.

Scientists who did not participate in the study agreed that it was highly significant. H. Jack West, an oncologist at the Swedish Medical Center in Seattle, said: "It's literally a change of practice, immediately."

Roy Herbst, an oncologist at the Yale Cancer Center, said that most patients with lung cancer will be offered immunotherapy in some way much sooner than before. Still, he said, the approach was not a cure and there is a lot of room for improvement. The estimated proportion of patients in the combination therapy group who were alive and whose disease had not worsened at one year was approximately 34 percent, approximately double the proportion for the chemotherapy alone group.

Last May, the Food and Drug Administration approved the Keytruda-chemistry combination based on an early-stage trial. But many doctors did not adopt it because the trial was small and did not initially show a survival benefit, Gandhi said.

Experts said it was especially significant that the study showed that patients benefited from the Keytruda-chemotherapy combination regardless of the levels of a protein, called PD-L1, found in their cancer cells. Researchers already knew that patients with high levels of protein were more likely to respond to immunotherapy.

Last week, in a related development, Merck, which makes Keytruda, reported that a different trial showed that medication prolonged survival even when used alone, compared with chemotherapy. Experts said they will have to see more details before they can determine if the drug is best used alone or with chemotherapy.

In a second study published Monday, researchers used two other immunotherapy drugs: Opdivo and Yervoy, both manufactured by Bristol. Myers Squibb: to treat newly diagnosed patients with advanced non-small cell lung cancer with a high number of mutations in their tumors.

Patients experienced a significantly longer period during which their disease did not get worse, compared to people who received only chemotherapy, said Memorial Sloan Kettering Cancer Center oncologist Matthew Hellman, who led the study.

He said the results established the combination of dual immunotherapy as a first-line treatment for patients with a high "tumor mutation load", but it was too early to know if the treatment leads to longer survival. And he said the trial showed that "tumor tumor burden" is a reliable way to predict who will benefit from medications.

Another study published on Monday used immunotherapy in a different way: for patients with early-stage lung cancer. Researchers at Johns Hopkins and Memorial Sloan Kettering gave patients two doses of Opdivo, the first one month before surgery, the second two weeks before the operation, to try to stimulate antitumor activity and reduce the risk of relapse.

Nine of the 20 patients who received Opdivo had an "important pathological response," the researchers said. That means that the tumors removed in the surgery had at least 10 percent fewer cancer cells than before the treatment.

Drew Pardoll, director of the Bloomberg-Kimmel Institute of Cancer Immunotherapy at Hopkins, said it's too early to know whether the findings will translate into longer survival. But if future studies show that, he added, immunotherapy could be used to increase or even replace the chemotherapy normally administered before surgery.